Railway vehicle wheel brake unit

ABSTRACT

A railway wheel brake unit, having a pivoted brake shoe lever moved by a piston into braking braking position by means of the engagement with a slack-adjusting mechanism and forced by a spring away from braking position, includes a pivoted coupling member on the brake shoe lever with a V-shaped groove registering a V-shaped end pushing member on the slack adjusting mechanism to thereby permit sliding engagement in the plane of movement of the brake shoe lever without rotation.

United States Patent Inventor Gert Artur Persson Oxie, Sweden Nils BorgeLennart Sander Malmo. Sweden Appl. No. 778,394 Filed Nov. 25, 1968Patented Mar. 30, 1971 Assignee Svenska Aktiebolaget BromsregulatorMalmo, Sweden RAILWAY VEHICLE WHEEL BRAKE UNIT 2 Claims, 2 Drawing Figs.

US. Cl 188/202, 188/217 Int. Cl Fl6d 65/56 Field of Search 188/52,

153, 196 (PRR), l98-203 (S), 217

[56] References Cited UNITED STATES PATENTS 3,430,740 3/1969 Larsson etal l88/202(S) FOREIGN PATENTS 450,481 4/1968 Switzerland 1,88/203(S)Primary ExaminerDuane A. Reger Attorney-Laurence R. Brown ABSTRACT: Arailway wheel brake unit, having a pivoted brake shoe lever moved by apiston into braking braking position by means of the engagement with aslack-adjusting mechanism and forced by a spring away from brakingposition, includes a pivoted coupling member on the brake shoe leverwith a V-shaped groove registering a V-shaped end pushing member on theslack adjusting mechanism to thereby permit sliding engagement in theplane of movement of the brake shoe lever without rotation.

Fig. 2

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ATTORNEY RAILWAY VEHICLE WHEEL BRAKE UNIT This invention relates to arailway vehicle wheel brake unit of the kind comprising a housing, abrake lever pivotally mounted in the housing, a brake shoe movablysupported outside the housing, a piston for moving the brake lever andtransmission means for transmitting brake-applying force from the brakelever to the brake shoe for applying the brake to an adjacent vehiclewheel, and a piston return spring to move the piston and brake lever forreleasing the brake from the vehicle wheel.

Brake units of the kind referred to are employed, for example, onvehicles such as locomotives and powered rail cars where the spacerequired by conventional brake riggings is not available, and one brakeunit being of suitably small outer dimensions can readily be mountedadjacent to each wheel of a vehicle.

In known brake units of the kind referred to the said transmission meansfor transmitting braking force from the brake lever to the brake shoefor applying the brake usually include one or more pivotal connections,and may include parts of an automatic slack-adjusting device. This saidpivotal connection or connections must allow the brake shoe to move in acircular path when the brake shoe is supported by a suspension arm, andthe pivotal motions of the brake lever must also be accommodated. Thebrake block is subject to vibrations during normal running of thevehicle as well as during braking, and it is a disadvantage that suchvibrations may cause unintended relative movements of the automaticslack-adjusting device.

The present invention is therefore intended to'provide an improved brakeunit of the kind referred to and such that the said disadvantage isreduced or obviated.

According to the present invention a brake unit ,of the kind referred tois characterized in that the said transmission means includes a pushmember constituted by a threaded spindle of an automatic slack adjuster,the other end of said spindle engaging a counterthrust memberconstituted by a pivotally mounted block through contact surfaces havingV-shape in horizontal section so as to allow relative movements invertical direction, but preventing relative rotational movements.Further and optional features of the invention appear from the followingdescription and are set forth in the appended claims.

in the accompanying drawing a brake unit in accordance with theinvention is illustrated partly diagrammatically and by way of example.

FIG. 1 being a view of the brake unit partially in vertical section; and

FIG. 2 being a detail view in section on the line 11-11 in FIG. 1.

The illustrated brake unit is shown in the brake-released condition andcomprises a housing 1, a brake lever 2 pivotally mounted on a pivot pin3 in the housing 1, a piston rod 4 pivotally connected to the brakelever 2, and a piston 5 rigidly connected to the piston rod 4 and actedupon by a piston return compression spring 6. The piston 5 is movable incylinder 7 rigidly connected to the housing 1 and having a top coverportion 8 clamped thereon. Between said cylinder 7 and said top coverportion 8 is clamped a flexible diaphragm 9. The piston 5 is movedtowards the brake-applying position by the flexible diaphragm 9 whencompressed air is fed to the space between the diaphragm 9 and the topcover portion 8.

A brake shoe 10 is pivotally connected to a suspension arm 11 which inturn is pivotally connected to a bracket 12 integral with the housing 1to move in a pivot plane parallel to the view of FIG. 1. The brake shoe10 carries a brake block 13 adapted to engage a vehicle wheel 14indicated by a dash-dotted line. The suspension arm 11 is provided witha pin 15 which extends through an elongated eye at the outer end of anaxially movable rod 16 extending into the housing 1. The rod 16 thus hasa lost motion connection with the suspension arm 11, and the inner endof said rod 16 is provided with a spring abutment 17 against which acompression spring 18 presses. The said spring 18 also bears against acover 19 rigidly connected to the housing 1. The suspension arm 11carries a coupling member block 20 having a vertical groove of V-shapetaken in horizontal section extending into the sheet as shown in H6. 2.Thespring 18 acts as a return spring, urging the arm 11 and brake shoe10 away from the wheel 14 and towards the released brake position andurging the block 20 towards a screw-threaded axially movable spindle 21the outer end of which has a complementary V-shaped end pusher portion41 to engage in the groove of the block 20. The V-shaped groove 40 andthe V-shaped end portion have apices lying in or parallel to the planeof movement of the pivoting lever 11 to produce free vertical slidingmovement as referenced to the drawing sheet.

The spindle 21 constitutes a push member, and the block 20 constitutes acounterthrust member, these two members 21 and 20 being thus arranged topress against one another for transmitting the brake-applying force, butthese two members 20 and 21 are disposed so that tension forces orforces in vertical directions cannot be transmitted from one to theother of these two members. The block 20 is pivotally mounted on a pivotpin 34 by which the brake shoe 10 is pivotally connected to thesuspension arm 11 which supports the brake shoe 10.

The brake unit incorporates an automatic slack-adjusting device whichincludes the screw-threaded spindle 21. The spindle 21 does not rotatebecause of the engagement of its V- shaped end portion in the groove ofthe block 20. When the brake is released the axial position of thespindle 21 is determined by two nuts 22 and 23 engaging an inwardlyextending flange 24 on a sleeve 25 guided radially in the housing 1 andguided and moved axially by the brake lever 2. The sleeve 25 and thusthe two nuts 22 and 23 may be manually rotated by rotation of a sleeve26 having an outwardly extending ridge 27 engaging a correspondinglyshaped axially extending groove 28 in the sleeve 25. The sleeve 26 isprovided with a cover 29 having a square head 30 protruding from a cover31 rigidly secured to the housing 1 for effecting manual rotation.Before such manual rotation can be carried out a locking pin 32extending through the cover 31 into a slot in the sleeve 26 must bewithdrawn from said slot in the sleeve 26 by pulling on a handle ringagainst the action of a compression return spring. The sleeve 26 isprovided with several slots disposed over its circumference and adaptedto be engaged by the locking pin 32. Thus it will be easy to obtain asuitable locking position, and after manual rotation the engagementbetween the lever 2 and the sleeve 25 will probably be at a differentpart of the circumference of the sleeve 25.

A two-armed lever 33 is pivotally mounted in the housing 1, the lowerend of said lever 33 being adapted to engage the brake lever 2 and theupper end of the lever 33 protruding from the housing 1 being adapted tobe engaged by a hand brake linkage.

Flexible dirt-excluding covers 35 and 36 are provided in known manner,and the housing 1 has conventional apertured lugs 37 for bolting tosuitable parts of the vehicle chassis.

The brake unit as shown and described will function as follows:

When compressed air is supplied to the space between the top coverportion 8 and the flexible diaphragm 9, the said diaphragm 9 will engagethe piston Sand move said piston 5 and the piston rod 4 towards the leftas viewed in FIG. 1. The brake lever 2 will be turned counterclockwisearound the pivot 3 and move the sleeve 25 axially towards the left. Thetwo nuts 22 and 23 and the spindle 21 will participate in the axialmovement of the sleeve 25 and cause the block 20, the brake shoe l0 andthe brake block 13 to perform a movement towards the left, following apath defined by the suspension arm 11. This movement is stopped by thecontact between the brake block 13 and the adjacent wheel 14. Themovements of the above-mentioned elements from their released brakepositions to their applied brake positions are opposed by the spring 18urging the rod 16 and thus the pin 15 towards the right as viewed inFIG. 1. Owing to the fact that the engagement by pressure between theblock 20 and the spindle 21 is not able to transmit tension forces thepiston return spring 6 is not able to retract the brake shoe 10 from itsapplied brake position but the shoe is retracted away from the wheel 14by the separate spring 18 when the compressed air is exhausted and thepiston 5 moves towards the right.

It will be understood that in the illustrated brake unit according tothe invention the spindle 21 will be prevented from unintended rotationsand will be substantially isolated from vertical vibrations and shocksfrom the brake block 13 and the brake shoe 10. Furthermore, the guidingof the sleeve 25 in its radial direction can be effected without regardto the circular path of the brake shoe l0 defined by the suspension arm1 l.

The invention is not limited to the use of a slack-adjuster or of anyspecial type of slack-adjuster in the brake unit. The illustrated brakeunit comprises an automatic slack-adjuster similar in many respects tothe type described in the US. Pat. application Ser. No. 662,446 (PatentNo. 3,430,740) but this is not a necessary limitation of the use of theinvention.

We claim:

1. An improvement in a railway vehicle brake unit of the kind having apivotally mounted brake lever moving in a pivot ing rotary movement ofsaid push member wherein the coupling member includes a block pivotallymounted on the brake lever with a groove therein lying in or parallelwith said pivot plane, and projection means .on the end of said pushmember registering in said groove.

2. The improvement defined in claim 1 wherein said groove is V-shapedand the corresponding projection means registering therein is V-shaped.

1. An improvement in a railway vehicle brake unit of the kind having apivotally mounted brake lever moving in a pivot plane and having a brakeshoe coupled thereto, a linkage moving the brake lever to contact thebrake shoe with a wheel on said vehicle, and spring means to move thelinkage and brake shoe away from the wheel, comprising in combination,transmission means in said linkage including a push member constitutingthe end of a threaded spindle of an automatic slack adjuster, and acoupling member between said brake lever and said push member permittingsaid lever and said push member to move relatively with respect to saidpivot plane but preventing rotary movement of said push member whereinthe coupling member includes a block pivotally mounted on the brakelever with a groove therein lying in or parallel with said pivot plane,and projection means on the end of said push member registering in saidgroove.
 2. The improvement defined in claim 1 wherein said groove isV-shaped and the corresponding projection means registering therein isV-shaped.